Which medication should be avoided with lithium treatment due to potential interaction?

• A. Paracetamol
• B. Ibuprofen
• C. Amlodipine
• D. Gaviscon

Answer: (B)

Lithium is cleared almost entirely by the kidneys and has a very narrow therapeutic window, so anything that reduces renal elimination can raise lithium levels and increase the risk of toxicity. Ibuprofen is an NSAID that can decrease kidney perfusion by inhibiting prostaglandin synthesis, which in turn reduces lithium excretion. Because of this, ibuprofen should be avoided or used with caution in someone taking lithium; if pain relief is needed, safer alternatives like paracetamol are preferred, or NSAIDs should be used for the shortest possible time with close monitoring of lithium levels and kidney function if they must be used.

Paracetamol is generally safe with lithium and can be used for pain relief. Amlodipine does not have a meaningful interaction with lithium, so it won’t significantly affect lithium levels. Gaviscon (an antacid) isn’t known to cause a clinically important interaction with lithium. Keeping well-hydrated and maintaining a normal salt intake helps keep lithium levels stable.